Hot-box detector



May 9, 1951 c. A. GALLAGHR Erm. Re. 24,983

HOT-BOX DETECTOR original Filed June so, 1958 3 Sheets-Sheet 1 L lv? uw@ @bf2/LJ v May 9, 1961 c. A. GALLAGHER ETAL Re. 24,983

' HOT-Box DETECTOR original Fillegjmego., 195g s sheets-sheet 2 INVENTO R5 Cap/vf; my ,4. 4144 LA arse ML f. Mw M Pf; wa

ATTO RN EY5 May 9, 1961 C. A. GALLAGHER I'AL HOT-Box DETECTOR original Filed June so, 195e :s sheets-Sheet :s

there being a unit on each side of the track to monitor simultaneously journal-box temperatures at both ends of the same axle.

Since hot-boxes are primarily `a problem with freight cars, the rolling stock shown in Fig. l is a freight car having a main frame 19 overhanging the side frame 20 ofone of its trucks, the journal box 18 forming an integral part embodiment illustrated in Fig. 2 slopes upwardly at an acute angle a which is preferably of the order of 2-0 to 50 degrees with the horizontal, and is aligned to observe the part of the journal box body which projects outwardly of the side frame 20; we have obtained very satisfactory results when the viewing angle was approximately 3S degrees in the vertical plane which paralleled the adjacent track 13.

It is to be noted that since the car frame 19 overhangs the journal box 18, -the viewing thereof is such as to establish a more or less quiescent background level for the cell 14. In other words, except for the intervals between adjacent cars, the viewing axis 16 will either look directly at the underside of the car frame 19 or at a part of the journal box 18.

Thus, for this embodiment of forward-aspect viewing, that is, for a car 19 rolling in the direction toward the detector unit 10 (right to left in the sense of Fig. 1), the image 17 will first intercept the box 18 along the top edge 22 of the front lateral side 23. As the car proceeds further toward the detector 10, the image 17 scans down a path 24 on the front side 23 of the box 18, and for the box configuration shown, viewing on axis 16 will cover the whole side 23 and most of the bottom of the box 18. The important point to note about forward-aspect viewing (that is, viewing the oncoming or forward side of each journal box) is that the cell image 17 moves sharply from the relatively uniform and cool background level 'represented by the underside of the car 19 to the relatively warm upper edge 22 of the box 18. There is no gradual transition of temperature and, on the other hand, the gradient is virtually optimum, inasmuch as the upper part of a journal box is always the warmest part.

, For trailing-aspect viewing, that is, for the situation in which the car 19 is traveling away from thev detector 10 (left to right, in fthe sense of Fig 1), the viewing axis 16 will first intercept the box 18 on its underside, whichis always cool relative to lthe upper side.v Thus, the transition from low background level on the underside of the car to the level von the bottom of the box 18 will not involve as great a change in temperatureas for the forward-viewing aspect situation described above. For trailing aspect, however, the temperature profile along the scanned path 24 will be steadilyrising as ythe image 17 risesup the side 23, and the hottest part vof the box will bethe last viewed region. v

, .Ordinarly,v the cooling effect of ,onrushing air v against the front side of ajournal box, as compared with the relatively stagnant airon the rear `or trailing side ofl a journal box, is sucient to account for a considerable difference in measurable temperature-between that at the top of the forward side of the .box,as compared with that at the top of the trailing side of the-journal box. Thus, it might be argued that best viewing is necessarily fora trailing aspect. Thismay all very well be -true if the train is passing by at sucient speed` so that the detector cell 14 does not become insensitive. Howevenforslower speeds, system responseis definitely degraded (because of of the truck structure 20; The viewing axis 16 in the,y

However, from the standpoint of cleanliness of the lens, trailing-aspect viewing is better, since the air stream from passing trains tends to sweep dirt away from the lens.

Our improved detector is equally applicable to forward, vertical or to rear-aspect viewing, but for the case of Fig. 3, forward-aspect viewing will be assumed; thus, the car 19 and its wheel 25 will be assumed to be rolling toward the detector unit 10 so that the cell 14 will be subject'to the sudden change in temperature which occurs when the image 17 is first intercepted by the upper part of the side 23 of the jour-nal box. For the arrangement shown, the

cell 14 is employed in a polarized bridge circuit in which" a similarl'cell element 26 is also connected; the element 26 is shielded, as suggested at 27, so as to provide'an ambient or reference response against which the transientV response of cell 14 may be compared. Bridge output passes first to a pre-amplifier 28 and then to a signalamplifier 29, and, for certain applications, it is .suicient directly to utilize the heat-signal output of the amplifier 29, as by feeding the same to arecorder 30 and to alarm and telemetering means 31-32, as needed; alarnrm'eans 32 will be understood to function above a preset signal threshold level, representing a safety limit of journal-box temperature, as explained in said copendingl application. However, in the preferred form, we employa gate"33 for the purpose of excluding all heat signals not attributable directly to response to the journal box 18. l The gate '33 may be triggered by a's'uitable'wheeltrip, shown only in dotted outline 34 in Figs. l 'and 2, but described in complete 'detail in copending applica-v tion Serial No. 627,330, tiled December 10, 1956, 'inftliel name of Cornelius A. Gallagher et al. For installationsY employing separate detectors 10 on opposite sides of `the track, to monitor simultaneously both journal boxes, on the same axle, it will be understood that the same l 34 can serve both detectors 10. It sulices here to say that the trip 34 may be onev of. a number of varieties, and in said copending application the trip 3'4comprises merely a magnetic circuit including a gap which is-transiently closed by the flange of the wheel 25. A winding coupled to this magnetic circuit develops the `trip signal. Preferably, the wheel-trip means includes a storage circuit Vas, for example, a monostable multivibrator lolrfa time-delay drop-out relay, whereby the trip fed to the gate 33 for the purpose of opening the same of a duration great enough to allow cell response at to the top of side'23 of 'the journal box18. z

The location `of the wheel-trip 34 ywith respect tothe housing 10 should be ysuch that the gate 33 will open just prior ,to imaging the cell at the top edge 22, regardless of the speed of the train. The'len'gth of time that gate 33 remains openshould permit viewing of'tleast the upper'part of the side 23, even for the'slowesttrainsl For example, a gate interval of 5() milli-secondsisfound adequate even for trains passing- `at five milesj anf'fhour; such a gate interval is found to present no limitaticm,on`

detector performance, `even for the fastestfreight low-frequency limitations) if temperature rise injthe detector isi not fast enough, even though the ultimate total may be fairly substantial. 'Ihe above discusonly serves to pointV out that forward-aspect viewing may be preferred over trailing-aspect viewing because the of change ofmeasurable heat is greater, even though ymaximum observable heat may notbe of as great In order to protect theA internal parts Vof lthe housing 10 during periods 4when noA trains are passingwwe prefer to employ shutter means `36 to closefa'nd open afviewf ing aperture 'in the housing `10, theshutter means, V361 reslower speed trains, as for example/down vto five' an hour, the shutter 36 willY also-remain openfo all greater train speeds; yWhen the train passes completely, the'storage device"38 will *fail* to excite sfolenoid? andtheshutter 36 will close, a's by'spring v01j gravity- -magnitude as that observable with rear-aspect viewing. v vproblem of detecting hot-boxes on trainsjcoming alwa 'the eases..

inthe same direction down a givenlength of track beingv gardless of the direction of traic along the track; for

example, our. detector incorporates automatic means for sensing the direction of oncomingl traic and for selecte ing the appropriate response aspect in accordance with the sensed direction` of. tramo. ForVV such, purposes, we illustrate in Fig. 4 the employment of a detector assembly 10, comprising optical systems. having .essentially duplicate or conjugate response. axes 16`16 the axis 16 being as described. in connection withv Figs. l andz,y and the, axis 16' being the substantial.Vv reverse, ij.e., lookingin the opposite direction fromA the axis 1.6.

In the form shown in Fig, 4.duplicate detecting systems --41 are mounted on the chassis 42. Eacli such system is shown to comprise` a cell and an infra-red transmitting lens 44,-44', mounted in` an. adjustable focusing barrel 45-45'. Pre-amplifiers 46-46' may be mounted close. to, thel cells 43.-437, and the entire assembly isv contained within al rugged housing.I having slopingy side wallsV 47--48 toface oncoming trai.- lic. Openings. 49-50 in thewalls 47-48 permit viewing on n selected one of thevaxes.16..16.', when one of the shutters 51-52 has been'. actuated by its solenoid 53l or 54, as. the case may be.. The entire assembly. of internal components may be shock-mounted. as sugf gested at 55.

' For any particular desired viewing aspect, say, the. forward-viewing it will. be necessary to employ. arst wheel-trip, as at 34, to.- determine arstgatelopen ingffor trains approaching from the (in the of Fig. 2), and a second similar wheeletrip 56 ony other side of the detector 10, to determine a, second gate. opening for trains approaching from left to. right, in the sense of Fig. 2. These same two wheel-trips 3.4-r-.56 also preferably serve tov determine automatically the di-.. rection of approach of a particular passing train, for purposes of opening the correctshutter'Sl or 52, aswill' be made clear. from thediscussion of Fig.4 5.

In the arrangement of Fig. 5, thesymbolism and.[func.

y tiorfll functional. components follow generally thescheme illustrated in Fig. 3, except that thesystem is automatical-H ly responsive regardless of the direction of oncoming traftic. Thus, the electrical components, up to and includ-Y ing separate gates 51-57 rfor the respective. cells. 43,-43', correspond. withthose shown and at. 14e-33 in. connection with Fig, 3.

Now, for trains approaching. from: the right (inthe sense of Fig. 12), and. for the. assumed caseof forward aspect viewing, the viewing .axis 16, must be` utilized to..

. the exclusion of theviewing-axis16f. .To achieve selection automatically, we slmw` directiouallY-responsive switchingmeans 58 having thefinputs. connected to. both of the wheel-tripk devices 34-56 and electiye to respond directionally to the onset of the impulse re.- ceived fromr the lirst wheel-trip device to be'r .For the assumed case, such `first impulse be developedby the trip 34, which is thus elective to. the switching means. 58, in the sense establishingconnection` of the output of gate 57 to a single put line 59. Hadthe direction' of approachbeen from left to right (in the sense vof Pig. 2), trip 56would have developed the lrst control impulse, and' switching means. 58 would have been switchedto connect output of gate 57' tothe signal output line 59, as will be understood.

Since switching means 58,must change itsstate in order.J

to. tablish one or other-ofA described connections.

6 lS1, to the exclusion of shutter 52.y The heat signals developed in output line 59, therefore, correctly viewing on the 16, and itl will beunderstoodlthet [approach] approach offtrailc from the other the heatv signal (in lineg59) will reectY viewing only on the axis 16', to the exclusion of the airis 16. Once a selectedA one of the shutter-opening solenods has been operated, and assumingthat the passingtrain is proceeding virithsfufiA ficient speed, storage means 38 or 38', as the casemay be, is eective to maintainthe open-shutter connection aslojng as the train is passing.

The heat-signal present in line 59 may be fed to recorder, alarm, or telemetering means, as explained in connection with Fig. 3. 'Ihe functioning of such devices need not be dependent upon .the direction of passage of a train, and, therefore, a single relay 62, functioning, say, from the storage means 38', will sufce to develop a control signal for enabling or turning on the recorder, alarm, or telemetering means, only aslong as the train is the boxftemperature monitoringl point.

The. discussion above in connection with, the. cirmrits` ofA Figs. 3 and 5 has assumed the caseof forwardf y viewing on oncomingl journal boxes. In suchevent, itY has been explained that a constant relatively short-delay factor, or storage function, incorporated in the wheelf trip means 34 or 56, sullices to control the. gate 33,57`,

or'57'. This is because the detector responds bestto relatively quick: changm in heat, and for forward-aspect" .viewing:,tl1e greatest change will be observed when image 17 iirst strikes the top or. leadingy edge 21 of thel journal boxl 18; it really matters notl whatthe. rest of Athe heat prolle around the box` may be,A as'long asthis mist strongly contrasting heat change is observed; i

With trailing-aspect viewing, on the otIier-liantLfit` is; of greatest importance that the gate 33,k 57, or 57', once opened', shall remain open long enough for the 17 to scan all the way upto the top rear edge .of the' journal box. Naturally, the time requin-editoV achieve this will be. diEerent forwdierent train speeds, and in Fig. 6A we show a modiled trip device to meet the needfor adequateresponse, regardless of, train speed, particularly for trail?. ing-aspect viewing. In the arrangement of Eig. 6, eachA wheel-trip incorporates dual trip velements e-66, of which develops a separate, control pulse determining the' on" andthe of' functioning..y ota dip-dop circuit' 67. By setting the spacingl D between trips 65,--66 to correspond to kthe eifective. projected.` observablei W of a ournal box, one can be sure that the. Sillalflinllit from the ip-iiop circuit 67 is a square gatingfpulae tive. to control the gate during the full period of exposure` tothe journal box; ByA inspectionof the trigonometiy O tion' of approach of a, train. In the form shown, apl'ane mirror 70 is pilwtedl at 7,1 andpoeitionable either as shown in full lines or as shown iny dashed 10,', solenqids 'lz-7sare in actuating relation with mirm'rlu and they respondY to directionally responsive relay-means.- 74v in' vthe manner descrbedgat; 534-54-4-58v inFigf. Thus, for forward-aspect' viewing, and I'for al trainap proaching from right to left in thesense of'lig, 7,. trip 34` will be actuated prior to trip 56, thereby causingrelay to signal-output line'59, we use such change of state as f solenoids 53-54, as suggested lby connections 0f-61. 'lhuacoincidentally with connecting gate 57 to output line 59, solenoid'SSis actuated to'open the shutter Vsrneans for controlling operation of one of Vthe shutter Y 74 to VmunitesolenoidA wandte move 'm to the.' position" shown 'in fullv outline, whereby shutter y514 opened and cell 14 is caused to 16, 'via mirror 70: with .a Suitable delayed-drown: tunctiontor. relax 74, this mechanicalsettingmay be maintained fortliejirll lenathf ofthe pwins'trin- For mma-lacet Viewilnl agees 7 of trains approaching in the opposite direction, relay 74 be eEective to set and hold mirror 70 in the positionv 70' and to yopen shutter 52, thus causing cell 14 to view on .the axis 16' via mirror 70. For trailing-aspect viewing the control function of relay 74 will be understood to be reversed from that described for forward-aspect viewing.

. The aspect of viewing constitutes an important part of our invention. As explained previously, the prior axial end-on viewing has never met with commercial success becauseof the many disadvantages discussed earlier in the speciication. Slant-aspect viewing solved many of thel problems existent in the prior devices.

Other aspects of viewing which may also `be satisfactorily utilized are illustrated in Figs. 8-11. k

,Referring first to Fig. 8, the detectors 10 are mounted inside the tracks 13 for viewing the wheel-axle junctions 78. It is now known that the heat in the wheel-axle junct'ion is related to theheat inthe journal box. The journal box condition may, therefore, be investigated by detecting the heat at the wheel-axle junction. Thus, in this embodiment, the detectors are mounted for slant-aspect viewing, but of the wheel-axle junctions rather than of the journal boxes. The wheel-trip devices and the cuits :for applying the heat signal information to the telemetering equipment are the same as previously described and, therefore, have been omitted from this igure.l

' Fig. 9 is an alternative arrangement of that shown in Fig. 8. In this arrangement, the detectors are mounted for vertical-aspect viewing of the wheel-axle junction. Although this arrangement has the disadvantage ofthe detector being exposed more fully to dirt, weather, etc., ithas certain definite advantages. For exampleone view- [Furthenthere is less possibility of the detectorviewing sky and other extraneous background which may 'cause false signal indications] Y Fig. l illustrates an alternative embodiment ofslantaspect viewing 'differing somewhat from Fig. 1. In Fig. l, the viewing image axis is in a plane parallel tothe track. In Fig. 10, however, the detector is mounted at an angle, for example 10 degrees, to the track and either at track level or between tracklevel and the plane of the journal box. With the detector 10 at tracklevel, there is little real dierence between they two embodiments; however, with the detector elevated to a position the track level and the plane of the'journal box, are several real advantages in thisembodiment. Y

"For example, detection of direct sunlight andV sun re'- lectious ,is lcsslikely with the horizontal-plane viewing.; [Eurthen the body ofthe carprovides a background for thedetector, whereas in slant-aspect viewing the vbackground ver'y often is sky.] .'Moreover, 'with the detector mounted at an angle to the track and raised from the track bed, vgreater exibility of vertical `angle viewing is poslible." f Y Fig. 11 illustrates still another of journal box fiewing. In Fig. l, the image-of the heat-sensitive cell raverses a hot-box portion forward of the frame 20.` -In `General-ly, an area 3" wide isaccessible for scanning it rear 'of the frame with no obstructions in the field lfvew. The uniformity -cfg-heat information for this L rea' of scan has been l o thaty obtained by scanning .the forward portion of the curnal o sunlight relections. .y v Y l p It be seen that we have described a relatively simie`,detector rnechaxiisml having improvedffmeansdfor isciiminating troublesome hot-boxes. With our arrange; rent, ,the discrimination problem itself is in fact simpliin thatthe background level is "not cluttered with '1e numerous heat vsinuses which ,have previously served ixly to' mask the desired journal-box signals. Further-l Fig. 1l, the journal housing `behindthe frame .is being found 'excellent and even superior ingJunit is suiiicient for detecting traflic in either` direction.

box. This form of scanniugis also less-subject 8 more, our improved viewing aspects provide for greatest rate-of change of observable journal-box signal, regardless of train speed, for virtually the entire range of train speeds. Also, our device lends itself to ciective operation in the presence of bi-directional traihc on the same length of track.

While we Ahave described our invention in detail forA the preferred forms shown, it will be understood that modications may be made within the scope of the invention as defined in the claims which follow.

We claim:

11. A 4railroad hot-box detecting device, comprising a housing mounted alongside a length of railroad track, said housing containing an infrared-radiation detector producing an electrical signal in response to incident radiant energy, said housing having a viewing opening therein, optical means Within said housing and imaging said detector externallyy of said housing and along au axis passing through said opening and in a direction to view passing journal boxes or axles, shutter means carried by said housing externally of said optical means and having an open position externally exposing said detector on Ysaid axis, said shutter means having a closed position closing said opening and protecting both said optical means and said detector, whereby said detector is necessarily exposed to an internal part of said shutter means when in closed position, actuating means for said shutter means' including a wheel-operated trip responsive tothe presence of a wheel on the track near said housing and producing an electrical impulse for each passing wheel, said actuating means further including a storage device operated by such impulses, said storage device having a time constant at least sutlicient to keep said shutter means continuously openfor recurring wheel-trip impulses of a vperiodicity representing relatively slow passage of a train past said hot-box detecting device.

2. A railroad hot-box detecting device, comprising a housing mounted alongside a length of railroad track,

said housing containing aur infrared-radiation detector` producing an electrical signal in response to incident radiant energy, said housing having a viewing opening therein, optical means within said housing and imaging said detector externally of said housing and'alongan axis passing through said opening and in a direction to.' view passing journal boxes or axles, shutter means carried by said housing externally of said optical means and having an open position externally exposing said detector on said axis, said shlutter means having a closed position closing-said opening andprotecting .both said optical means and said detecten-whereby said 'detector is necessarily exposed to an internal part' of said shutter means when in closed position, and actuating means for said shutter means comprising a vdevice 'responsive to the presence of attain-on said track and actuating said shut-A position only substantially as long asv producing anl electrical signal in response to incidenty radiant energy, said `housing having a'viewing opening therein, optical'means-within said housing and imagingl said detector Yexternallyof said housing and along an axis passing vthrough said Aopening and'in la direction to f view passingl journal boxesor1axles, shutter means carried by said housing externallyof said optical means and having an open position externally exposing said detector on said axis, said shutter means having a closedV position closing saidopening and protecting both said optical frneansand. said' detectonwhereby said detector is necessarily exposed. vtoanint'erual '-p'art'ovf said shutter means whennaclosedpos'itiom' and actuating means for-said shutter, meansfincluding a storage circuit and a wheel'- operatori` generator4 connected to. said .storageffcircl'ritV andv s l producing an electrical vimpulse. for: zeach passing wheel, 75, l

said storage circuit having an input adapted to receive an impulse signal, said storage circuit producing a shutter- References Cited in the iile of this patent opening signal for said shutter means in response to an 01' the 011811131' Patent input impulse signal and having a storage time constant eiective to hold said shutter means open for a period of UNITED STATES PATENTS time at least equal to the greatest interval between suc- 5 1,972,682 FitzGerald Sept. 4, 1934 cessive wheel-trip impulses for a passing train traveling 1,985,563 FitzGerald DCC. 25. 1934 at the minimum response speed of said hot-box detecting 2,341,545 Hagenbook Feb. l5. 1944 device. 2,818,508 Johanson et al Dec.31,A 1957 storage circuit being adapted to close said shutter means 10 upon lapse of said period of time. 

